If it's a 2wd replace at least in pairs (front or rear) if it's a 4wd must replace all four. They are a little smaller. Make your speedometer read a little slow
Normally. yes.
No, there is too big a difference in diameter.
no there is too much height difference
Yes, that is a pretty good substitute.
215 65 r 15 or 205 60 r 15
Yes, if you can live with an inaccurate speedometer.
Yes, that is reasonable as long as both sides match.
The 205/70/r15 is 26.3 inches tall. The 215/65/r16 is 27 inches tall. Never mix different size tires on different rims.
Can you put a 215 70 r15 tire and a 215 65 r15 tire on same car
Yes, this is a good alternative. Your speedometer will be only be 0.6 mph too fast.
Can you replace 205/65/R15 with 205/75/R15
Yes, this is not a bad swap but know your speedometer will read 59.2 at a true 60 mph.